TECHNOLOGY
CO2
LASERS
bands at different wavelengths and it is important not to jump from wavelength to wavelength,’ says Held. ‘A lot of these materials are complex and, as you design the laser with the customer, you can go back and have them tweak their process. If you can move an absorption band one way or another, that helps.’ To overcome band drift or jump issues that could eliminate gains made with material changes, Held explains that there are certain ‘tricks’ that can be employed to lock the lasers at very specific wavelengths. Coherent’s work with its customers is now so close that lasers it can offer its clients may not even appear in the company brochures. ‘We need to develop the lasers quickly so you may not see them on a data sheet – but they are available to our customers,’ says Held.
Jason Bethel is Synrad’s chief scientist. He told Electro Optics: ‘We mainly manufacture lower-power CO2
40 microseconds, versus Synrad’s CW models that are at 75 microseconds.
Bethel says: ‘Most competitive CO2 lasers on the market are either CW or have peak powers around twice the average power.’
Bethel adds that such a laser ‘gives finer cut quality and can cut quicker in some applications. The product is for improved cutting speeds without additional costs.’ Heat-affected zones
also present less of a problem. Bethel adds that Synrad’s latest 400W lasers, which are CW, are 12 per cent more efficient than past 400W products. For Bethel, CO2
can compete on
cost and its beam quality is ‘usually pretty good, which has a big effect on the performance of the laser when used in applications.’ One such new application is marking food materials. Bethel is confident about the future:
‘One thing I remember is that more than 20 years ago people said gas/ CO2
, lasers would be all replaced by solid state lasers in the next five years, but there are just so many applications that CO2
lasers can
perform very well that fibre lasers cannot, and maybe never will. ‘I cannot see that five-year
prediction coming true anytime soon.’ l
lasers, not the multi-kilowatt systems for welding, cutting and high-power industrial processes.’ Bethel has a similar view to Held’s, in that CO2
has a future beyond
metals, with other materials that have good absorption at carbon dioxide’s wavelengths. ‘The big advantage that CO2
has is better absorption
for material such as wood, which is where we sell a lot of our products. For marking certain organic products, CO2
lasers have an advantage.’ One industrial example is the automotive industry, where organic materials in car interiors can be
processed with the longer CO2 wavelengths. Organic materials include, plastics, wood, paper and cardboard. CO2
lasers can operate at
9.3, 9.6 and 10.3 microns – so, where applicable, these wavelengths can be chosen to best suit the absorption characteristics of the materials. According to Bethel, his Pulsestar laser has higher peak power lasers in its class. It
100 CO2 than similar CO2
operates as a modulated continuous wave but it can also be considered as a quasi-pulse laser. It has a peak power of about four times the average, with faster rise times of
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